Alright, so looking around here and other places I see that this Netgear AC1900 (R7000) isn't optimally the best with stock firmware (cannot get to dnsmasq). Which router has the best compatibility with Pi-hole and all it's features (including the Pi-hole as a LAN DNS server)?
I couldn't tell you if it's the best but I have had continued success with the Linksys WRT1900acs v2 running DD-WRT.
Are you asking for a router to have Pi-hole running on it, or just a good WiFi router that plays well with Pi-hole as a DNS server?
If you're asking about a router to run Pi-hole, I can't offer any advice personally but I can recommend the ASUS AC-1990P as a great WiFi router.
If I understand your question, I think you'll want a router that can advertise the Pi's IP address as the DNS server (not the router's own IP address). That way, the queries come directly from the clients, the Pi knows which client sent which DNS query, and the reports and logs from Pi-hole become much more useful.
I know the Tomato firmware can be configured like this, and Cisco IOS routers work like this. I have used both successfully with Pi-hole on a Pi.
Any router that can install LEDE/DD-WRT/Tomato/Merlinwrt/Gargoyle etc. Some devices (like chromecast) have hardcoded DNS that can't be changed. With after-market firmware, you have the flexibility to "force" pi-hole by port forwarding lan-to-wan dns requests to the pi-hole. Factory firmware allow port forwarding only on the incoming WAN port.